1. Field of the Invention
The present invention relates to the stretching of magnetic particle-impregnated neurons and their axons by means of an external magnetic field and the use of such procedure for bridging gaps in damaged spinal cords and peripheral nerves for their repair and regeneration.
2. Background of Invention
Despite significant advances in our understanding of neurophysiology and spinal cord injury, a patient who sustains a complete spinal cord injury has little hope of recovery. Previous research has not yet yielded a way to stimulate the neuronal axons to regrow to replace the injured axonal structures and re-unite them with the motor neuron and, similarly, to replace the sensory axonal structures and unite them with their corresponding target cells. In other words, there has been some success in stimulating nerves to sprout, but not in directing that limited growth in a specifically-desired direction. To date, the only clinically effective treatment has been that of pharmacologic modification of the injury process to prevent further secondary damage to the spinal cord following the acute phase of the spinal cord injury. Thus, in most cases, damage to the spinal cord means permanent paralysis. The advice given on a hieroglyphic found in a pyramid from 2,500 B.C. that "this is a condition that cannot be treated" remains unfortunately largely true despite great effort. In the United States, there are approximately 250,000 individuals with permanent spinal cord injury with about 10,000 new cases each year. Paraplegia affects 55% of the spinal cord injured population, while 44% are affected by quadriplegia. According to the American Paralysis Association, the initial hospitalization averages $140,000 with an average lifetime cost of $1.2 million, depending on the severity of injury and age at which injury occurred. Christopher Reeves, who recently sustained a severe spinal cord injury, reports that his care costs $550,000 per year. More than 60% of the spinal cord injured population were between the ages of 16 and 30. The majority, 90% of spinal cord injured individuals, survive and live near normal life spans.
The present methodology and technology is applicable to the repair of spinal cord severance, but may also be applied to other causes of neuronal interruption including myelodysplasia, damage from herniated nucleus pulposus, and interruption of spinal cord function due to tumors or infection, as well as to interrupted or severed peripheral nerves, including nerves of the brachial plexus.
3. Prior Art
The most closely-related art known to the inventor is his own previous work related to cartilage repair, represented by Halpern, U.S. Pat. No. 5,655,546 (1997), in which magnetically-tagged particles are taken up by chondrocytes and directed to a cartilage defect site by magnetic implants at that site; whereas
Howard et al., U.S. Pat. No. 4,869,247 (1989) and Howard et al., U.S. Pat. No. 5,125,888 (1992) describe a system for the eradication of a tumor in which an electromagnetic field is positioned outside the body to deliver a small heat-sensitive pod or metal-tagged drug to any location in the brain or other body part. The small magnetic object, perhaps a ball, is inserted in the patient's head via a burr hole and magnetically manipulated to the tumor site. An energy beam is then directed at the magnetic object to accomplish destruction of the tumor. The metal-tagged drug is magnetically manipulated to a desired body part and the drug released by an energy beam which separates the drug from its magnetic counterpart; and PA1 Aebischer et al., U.S. Pat. No. 5,092,871 (1992) describe an electrically-charged nerve guidance channel for repairing severed nerve ends. In this device, the nerve ends are placed in proximity to each other within the lumen of the guidance channel, the idea being to promote repair. PA1 A composite comprising multiple strands of biodegradable material, each strand comprising magnetic particles in spaced intervals along said strand and oriented along the axis thereof either on the surface or internally of said strand, said strands being held together in a biodegradable matrix or mesh. PA1 method wherein the neurons and axons of said spinal cord or nerve are provided or loaded with magnetic nanoparticles in the area of the interruption or severance by injection of magnetic nanoparticles and causing said magnetic nanoparticles to be absorbed by said neurons and axons; such a PA1 method wherein said magnetic nanoparticles are complexed with or bonded to a substance which is taken up by the neurons and axons at the severed end of a damaged spinal cord or peripheral nerve and which is actively incorporated into the neurons and axons as a complex molecule; such a PA1 method wherein the magnetic nanoparticles are bonded to a substance selected from nerve growth factors, horseradish peroxidase, neurotrophic immunophylins, and active DNA or RNA strands; such a PA1 method wherein said magnetic nanoparticles are introduced into the neurons and axons by injection into the spinal canal intrathecally or at the site of the spinal cord or nerve interruption; such a PA1 method including the step of focusing and concentrating the external magnetic field along said axis; such a PA1 method wherein an insert, comprising a plurality of biodegradable strands comprising metallic particles in spaced intervals along said strands and oriented along the axis thereof either on the surface or internally of said strands, is surgically implanted along the axis of said spinal cord or nerve for focusing and concentrating the external magnetic field along said axis; such a PA1 method wherein said external magnetic field comprises a coil which is moveable longitudinally along the axis of the spinal cord or peripheral nerve to assist in such stretching and bridging; and such a PA1 method wherein the coil for creating the external magnetic field is adjustable so as better to follow and coincide with the angle of the spinal cord or peripheral nerve itself.
See also the additional U.S. Patents and Publications listed on the attached Invention Disclosure Statement (IDS).